In literature, the term “inciting incident” describes an event that propels the story forward, the stone thrown into water that disrupts the surface calm and sends out ripples that eventually reach shore. But it’s not merely a literary device. When poet Pamela Harrison was a child, a fateful afternoon transformed her family’s life, and her life, in ways that she couldn’t begin to understand until years later, when she became a writer.

Harrison grew up in Oklahoma City in the 1950s. Her parents, Vera Alice Pritchett Harrison and Lynn Henry Harrison, had met at the University of Oklahoma Medical School, where Lynn was a student and Vera was a nurse.

Lynn Harrison was from Cortez, Colo., a Westerner who loved the region’s buffeting winds and pounding heat; Vera Pritchett was the daughter of an Oklahoma pioneer. Pritchett’s father had been part of the Oklahoma Land Rush of 1889, when thousands of settlers raced on horseback into Indian Territory in the hopes of staking their claims.

Vera was, Harrison said, a smart, feisty girl who used to sit on her father’s lap and read him the sports pages. Lynn was a charming, charismatic man. They had three children and a seemingly placid and orderly existence.

But, one afternoon, when Harrison was practicing for her piano lesson, her younger sister Stephanie came to her. “Mommy won’t wake up,” she said. It was the late 1950s and Harrison said she doesn’t remember her exact age, somewhere between 9 and 11.

Their mother was lying on the bed, eyes closed, hands crossed on her chest, shoes placed neatly on the floor. Harrison’s first thought was that maybe her mother was playing a game. A farm girl raised during the Dust Bowl wouldn’t lie casually on top of her best blue bedspread; that just wasn’t done. Harrison grabbed hold of her mother’s hand, but it was heavy and inert and slipped from her grasp, falling back to the bedspread.

Knowing something was wrong, she called to her older brother Lynn, who was in the house. He summoned their father from work. When their father came home, running up the stairs, he brought with him a strange-looking green tank with a long tube that he inserted into his wife’s mouth. A stomach pump. He knew what he could expect to find from his children’s descriptions of being unable to rouse their mother.

Their mother’s older sister Mae Pritchett was with him. The children were lined up in the room, Harrison said, like the three monkeys: See No Evil, Hear No Evil, Speak No Evil.

Their father prodded their mother’s eyelids open with his thumb, to look at her pupils. Coffee was made and father and aunt began, Harrison said, pouring it down her mother’s throat. But she was unresponsive and it spilled from her mouth. Together Lynn Harrison and Mae Pritchett pulled Vera off the bed, draped her arms around their shoulders, and began walking her up and down the room in front of the bewildered children, her feet dragging along the carpet, painted toenails little half-moons of color.

“There is always an aftermath to these parental difficulties, and that was the day I became a watcher. I think that’s what artists are,” Harrison said in an interview at her home in Norwich.

When their mother came back to consciousness, their father told them only, “Your Mom made a mistake and she was tired and she took the wrong pill.” It was never mentioned again, and none of the children understood what had happened until much later.

Their father had been having an affair with his secretary, and their mother had found him out. They remained married, but for nine years, Vera Alice kept her husband at arm’s length, punishing him with silence, and punishing herself with alcohol. The children were unaware of their parents’ turmoil. “They didn’t do emotional politics at all. They didn’t subject their children to it,” Harrison said.

Why her mother chose to try to kill herself with her three children in the house at the time is a mystery. Perhaps, Harrison said, she counted on her children finding her and raising the alarm in time. But she doesn’t know the reason, and her mother never said anything to her. “It’s terrible to have so much feeling and not have the words to speak. She obviously felt trapped and didn’t know how else to make her cry heard,” Harrison said.

It wasn’t until Lynn, the oldest of the children, began to coax his mother out of her depression and anger that husband and wife were able to reach an accepting accomodation of each other. “They truly loved each other; that’s how they could make each other so miserable,” Harrison said. “I’ll never know what (my mother’s) private thoughts were, she was worldless. I think part of the reason I’m a writer is because there were all these unspoken words rife in the house. We were a family that didn’t speak.”

Once her parents were dead, Harrison sought permission from her siblings to tell the story of her parents’ marriage in the 2009 volume of poems Out of Silence, which Harrison called “an eruption of all this buried, denied material.” Out of Silence was the follow-up to Harrison’s second book of poems, The Okie Chronicles, which told the same story, but in a more fictional fashion, with characters who were amalagams of her parents and other people. Harrison’s first full-length collection, Stereopticon, was published by David Roberts in 2004. In 2002, she was awarded the PEN Northern New England Discovery Award. She also received an M.F.A. in poetry from Vermont College.

Harrison’s new book What to Make of It, published by Turning Point, continues the story of her adult life: her 42-year marriage to Dennis McCullough, a doctor who was former chief of staff at Alice Peck Day Hospital in Lebanon, their adoption of their daughter Kate, and their travels overseas for McCullough’s medical work. McCullough is also the author of My Mother, Your Mother: Embracing “Slow Medicine,” the Compassionate Approach to Caring For Your Aging Loved Ones.

After such a long union, Harrison has learned that “you cannot judge a marriage from the outside.” What begins as infatuation transforms over time into something more considered and valuable, with mutual respect at its core. “The lucky thing was, we wrote into our marriage vows, I take you for what you are, and will be,” Harrison said.

They met when they were college students: Harrison was at Smith College and McCullough at Harvard. Introduced by a friend at a party at Harvard in 1969, they were married in 1971 and began a period of wandering, because of McCullough’s medical work in Finland, the Canadian Arctic, Uganda and Carriacou, in the West Indies, “serving these populations of people who were in crunching need,” Harrison said.

The feeling that comes through in What to Make of It is Harrison’s physical and verbal isolation, and how she grappled with it. Early on in their marriage, for example, they lived in Finland. But Harrison spoke no Finnish and very few Finns she encountered spoke English, which left her powerless in a way she hadn’t anticipated. She was alone during the day while her husband went to work. The only English language book she could find in a library was Sylvia Plath’s The Bell Jar, not necessarily the book you want to read when you are feeling sucked into a black hole of uncertainty.

“Before that time I never dreamed how much I needed language to sustain myself,” Harrison writes in the poem Words Deserted. “When words deserted me, whole days escaped in air.”

“I needed language to map this experience,” Harrison said. “I was writing letters home to Mom and Dad. I wanted them to experience this vivid visual memory of things, which has been the backbone of my poetry.”

Harrison cites as influences some of the giants: Robert Frost, Robert Penn Warren and Elizabeth Bishop, for the “specificity of her vision and being very present in a scene.”

As to her own poetry, Harrison is self-deprecating. “If I have any gift at all I think it’s my observing eye. That was the only gift I had to offer in those places, to offer an accurate account of what I saw.” But on the subject of language, and respecting what it can do, she is impassioned.

“I believe in the power of words, the power of well-chosen, thoughtful, careful words,” she said, her voice rising in emphasis. Poetry is an art form that demands concentration and focus from both writer and reader: you can’t just skim the words hoping to glean meaning. “You have to read word by word to experience the explosions each word is capable of setting off,” Harrison said.

Harrison and McCullough have lived in Norwich since 1986. Their daughter, Kate, now 36, lives in Seattle. A small woman with a round face and expressive eyes, Harrison loves the region’s soft green and abundant trees and flowers, a marked contrast to the plains of Oklahoma. A garden flows, in curving beds, around the perimeter of their house, showing off peonies and crane’s bill and feverfew. In a field below the house is a vegetable plot that McCullough tends.

In the fall of 2001 McCullough suffered a debilitating attack of reactive arthritis, which inflamed his joints and put him on crutches. In the process of caring for him, which included a stay in the Yucatan in Mexico, where McCullough could alleviate stress and swim in the warm waters of the Gulf of Mexico, Harrison learned that she could navigate foreign cultures, and look after her husband, in a way she hadn’t been able to when she was in her 20s.

She used the time to work on her poems. “You can imagine if your husband is sleeping 15 hours a day, I had a lot of quiet time to think and read and write.”

Now the couple have reached an understanding of what each other wants and needs. “We can be quiet together in the same space without feeling empty. This last great adventure, growing old and dying will be as interesting as anything we’ve done,” Harrison said.

Whether she’ll write more poetry is an open question. “I feel as if I’ve fallen into an enormous quiet. The wells of memory are pretty empty. If I’m going to write again, I’ll write again. I won’t second guess it.”

Right now, she said, her job is to look and listen to the world, to contemplate and to go back to work into her garden, where no words are needed at all.

Pamela Harrison will read for the Poetry Society of New Hampshire at Gibson’s Book Store in Concord at 7 p.m. on Aug. 21. For information, go to www.gibsonsbookstore.com or call 603-224-0562.